Metalloproteinase inhibitor 4 is an enzyme that in humans is encoded by the TIMP4 gene, belongs to the protease inhibitor I35 (TIMP) family. The protein complexes with metalloproteinases (such as collagenases) and irreversibly inactivates them by binding to their catalytic zinc cofactor. Known to act on MMP-1, MMP-2, MMP-3, MMP-7 and MMP-9.